/*
 * Copyright (c) 2024 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.koalaui.arkoala;

import java.util.HashMap;

class ResourceInfo {
    Object resource;
    int holdersCount;
    ResourceInfo(Object resource, int holdersCount) {
        this.resource = resource;
        this.holdersCount = holdersCount;
    }
}

public class ResourceHolder {
    private static int nextResourceId = 100;
    private HashMap<Integer, ResourceInfo> resources  = new HashMap<Integer, ResourceInfo>();
    private static ResourceHolder _instance = null;
    static ResourceHolder instance() {
        if (ResourceHolder._instance == null) {
            ResourceHolder._instance = new ResourceHolder();
        }
        return ResourceHolder._instance;
    }

    public void hold(int resourceId) {
        ResourceInfo info = this.resources.get(resourceId);
        if (info == null)
            throw new Error("Resource " + resourceId + " does not exists, can not hold");
        else
            info.holdersCount++;
    }

    public void release(int resourceId) {
        ResourceInfo resource = this.resources.get(resourceId);
        if (resource == null)
            throw new Error("Resource " + resourceId + " does not exists, can not release");
        resource.holdersCount--;
        if (resource.holdersCount <= 0)
            this.resources.remove(resourceId);
    }

    public int registerAndHold(Object resource) {
        int resourceId = ResourceHolder.nextResourceId++;
        this.resources.put(resourceId, new ResourceInfo(resource, 1));
        return resourceId;
    }
}
